Various gases, in particular hydrocarbons; such as, propane, butane and the like, are commonly stored in pressurized tanks for use, typically as fuels. The pressurized tanks contain valves through which the outflow of gas from the tank can be controlled. When pressurized tanks are not in use such valves are typically plugged in order to block the entry of dirt and to prevent damage to the interior of the valve and to help seal leakage of gas from the valve. For at least one type of pressurized gas tank, propane tanks, the type of valve unit in use has evolved over time into two different types of valve units, an old style valve unit referred to as a POL style valve and a newer style valve referred to as Type 1 connection valve. However, the Type 1 connection valve has not supplanted the POL valve, rather, both styles of valves are commonly in use. The same facility can even have propane tanks which use both styles of valves.
The POL valve unit has a single-seal valve which has a handwheel that when opened will freely discharge gas from a source of gas, such as a pressurized tank. The POL valve unit has a valve body which has a valve stem having an orifice through which the gas discharges. The base of the valve stem orifice typically has a tapered counterbore that can seal against the complimentary tapered end of a properly tightened appliance coupling. A typical appliance is a barbecue grill which requires a source of gas.
The Type 1 connection valve unit has a dual-seal valve with an internal backcheck valve module that is secondary to the handwheel operated primary seal. The Type 1 connection valve handwheel, even when opened, will not discharge a gas, such as propane, unless an appliance coupling is inserted. Specifically, the backcheck valve in the backcheck valve module blocks an outflow of gas unless an appliance coupling is inserted, which pushes the backcheck valve into an open position and allows gas to flow from the tank.
When POL valves are not in service they typically are sealed with a plug. These POL plugs are screwed into the internal left-hand thread that is typical of POL valve valve stems. Further, these plugs typically have end portions shaped similarly to an appliance coupling, and seal similarly against the tapered valve stem orifice counterbore. These plugs sometimes incorporate an O-ring which forms a seal against the tapered valve stem orifice counter bore. The new style Type 1 connection valve valve stem has internal left-hand threads similar to the old style POL valve, but also has an external thread on the walls forming the valve stem through which gas is supplied. A dust cap can be fastened to these external threads when the tank is not in service. However, because the internal threads are similar or the same on POL valves and Type 1 connection valves, the old style POL plug can also be screwed into the Type 1 connection valve. When this happens, the plug can come into contact with the backcheck valve and thereby push the valve into open position which can allow gas to leak from the tank if the handwheel is not completely closed. This can also permanently damage the backcheck valve. The additional protection that is intended by the backcheck valve is thereby overridden. To try and avoid this problem, tanks with Type 1 connection valves often include dust caps fastenable to the external threads and information on the use of dust caps and non-use of a plug to protect the orifice.
Therefore, presently, suppliers of pressurized gas tanks need to order, make available, and use two different types of protective devices for out-of-service pressurized gas tanks, a dust cap device for Type 1 connection valves, and a POL plug for POL valves. Further, the use of two devices including the old style POL plugs can allow for the detrimental, accidental use of POL plugs in Type 1 connection valves.
Accordingly, there is a need for a single type of gas tank valve plug that would safely and effectively fit both a Type 1 connection valve and a POL valve.